SetWindowsHookExW 未调用 MouseProc 回调过程

Question

所以我尝试用 C 语言运行一个简单的代码，在每次移动鼠标时打印鼠标的位置。为了让程序运行一段时间然后退出，我使用了如下所示的 for 循环。我希望挂钩仅与当前线程关联。 这是代码：

#include <stdio.h>
#include <windows.h>

// Global hook handle
HHOOK hHook = NULL;

// Mouse hook callback
LRESULT CALLBACK MouseHookProc(int nCode, WPARAM wParam, LPARAM lParam) {
    printf("Entered\n");

    if (nCode >= 0) {
        if ((nCode == HC_ACTION) && (wParam == WM_MOUSEMOVE)) {
            MOUSEHOOKSTRUCT* pMouseStruct = (MOUSEHOOKSTRUCT*)lParam;
            printf("Mouse X: %ld, Mouse Y: %ld\n", pMouseStruct->pt.x, pMouseStruct->pt.y);
        }
    }

    return CallNextHookEx(hHook, nCode, wParam, lParam);
}

int main() {
    // Install the mouse hook
    hHook = SetWindowsHookEx(WH_MOUSE, (HOOKPROC) &MouseHookProc, NULL, GetCurrentThreadId());

    if (hHook == NULL) {
        printf("Hook installation failed\n");
        return 1;
    }

    // Keep program running
    for (unsigned long long i = 0; i < 4e9; ++i) {}

    // Unhook and exit
    UnhookWindowsHookEx(hHook);
    return 0;
}

printf 语句永远不会被执行。为什么hook设置成功了，proc却没有被调用？

Answer 1

正如评论中所指出的，您确实需要一个 Win32 消息循环才能接收 挂钩事件。

• 获取消息：https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-getmessage

示例（main.cpp）：

#include <Windows.h>
#include <iostream>

static HHOOK p_hook = nullptr;

BOOL WINAPI HandlerRoutine(_In_ DWORD dwCtrlType);
LRESULT CALLBACK LowLevelMouseProc(_In_ int nCode, _In_ WPARAM wParam, _In_ LPARAM lParam);

int main()
{
    if (SetConsoleCtrlHandler(HandlerRoutine, TRUE) == 0)
        return ~0;

    p_hook = SetWindowsHookEx(WH_MOUSE_LL, LowLevelMouseProc, nullptr, 0);
    if (p_hook == nullptr)
        return ~0;

    MSG msg = { 0 };
    while (GetMessage(&msg, nullptr, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    if (p_hook != nullptr)
        UnhookWindowsHookEx(p_hook);

    return static_cast<int>(msg.wParam);
}

LRESULT CALLBACK LowLevelMouseProc(_In_ int nCode, _In_ WPARAM wParam, _In_ LPARAM lParam)
{
    if (nCode == HC_ACTION)
    {
        auto m_struct = reinterpret_cast<MSLLHOOKSTRUCT*>(lParam);
        std::cout << "x: " << m_struct->pt.x << " y: " << m_struct->pt.y << std::endl;
    }
    return CallNextHookEx(p_hook, nCode, wParam, lParam);
}

BOOL WINAPI HandlerRoutine(_In_ DWORD dwCtrlType)
{
    if (dwCtrlType == CTRL_CLOSE_EVENT || dwCtrlType == CTRL_SHUTDOWN_EVENT)
    {
        if (UnhookWindowsHookEx(p_hook) == TRUE)
            p_hook = nullptr;
    }
    return TRUE;
}